Thread: EDPM on flat roof

This is a ballast covered EDPM flat roof on a new warehouse. The builder claimed it was inspected and certified by the manufacturer of membrane, but I saw many uncovered spots and air bubbles on it.

The first photo is taken inside the inspected warehouse unit looking to the front door at south, no fastener (anchor) found on the ceiling (no back door, the north side is a back to back unit). The second photo is looking to north on the back to back unit showing the seam is flat and intact (I don't know why it was uncovered). The third photo is looking back to the inspected unit at south showing the air bubble along the partition wall, see close up on the forth photo. The fifth photo showing no Reinforced Perimeter Fastening Strip (RPF Strip), and the three remains showing the uncovered spots.

I am not a roofer, but it is unblievable that is a manufacturer certified roof, what do you think?

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Just so you report it correctly it is EPDM and that stands for "ethylene propylene diene monomer".

Well it does need some work, but I would not write it off. The seams are a little higher and tend to shed the ballast rocks, this is why they are not covered. The wrinkles need to be addressed as well as the bubble. Now that might not be a bubble, it is hard to tell. It might be a sloppy lap seal with lap tape and sealant. But, I think you are right about it being a bubble or wrinkle.

With a glued seam install and ballast you do not have an fasteners that you will see from the underside of the roof decking. The ballast is holding the membrane down.

I have attached one of the better install guides. It is by Firestone, but works well for just about every EPDM on the market.

Originally Posted by Daniel Leung

The builder claimed it was inspected and certified by the manufacturer of membrane

I am not a roofer, but it is unblievable that is a manufacturer certified roof, what do you think?

The easy way to find out is to ask the builder the manufacturer of the roof and call them, giving them the address of the building. Should only take the manufacturer a few seconds on the computer to locate it and confirm whether it was approved by them or not (of course, it may take minutes or hours for someone to spend those few seconds ... ).

The ballast is wind scorn. It's no big deal, but should be redistributed. A building with low parapet walls, probably no taller structures around to block the wind either. It'll happen again, and again, and again. I would recommend an annual maintenance program.

Some wrinkles are unavoidable on a loose laid system. As I recall, EPDM can be ordered in rolls that are 50' x 250'. Any wind during installation makes it a very difficult process.

The larger bubble in the 4th photo should be repaired, but I wouldn't make a big deal out of the smaller wrinkles.

Thanks for the replies and the installation guides. I believe it is not a manufacturer approved roof, because the builder cannot provide the mentioned manufacturer certificate or any information about the roofer. He emphasized the roof is under a 5-year warranty, but I'm still thinking the air bubble is a problem to be repair (it was soft and pressurized when I step on it).